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  • Note that evaluation for thoracic fluid is best performed as an extension of the RUQ and LUQ views by sliding the transducer up into the chest in a coronal plane.


  • A linear or convex transducer is preferred for evaluation of pneumothorax.

  • A convex or phased array transducer is preferred for evaluation of hemothorax.

  • The transducer indicator is oriented toward the patient’s head.

Suspected Pleural Fluid (Hemothorax)

  • With the indicator directed toward the patient’s head, the transducer is placed in the 5th or 6th intercostal space in the midaxillary line.

  • Identify the liver (on the right) or the spleen (on the left), the diaphragm, and the vertebral bodies that lie at the bottom of the screen.

  • In the fully inflated healthy lung, air prevents direct visualization of structures deep to the interface of the diaphragm and the visceral pleura of the lung. If fluid is present, it is identified as an anechoic (black) area that is caudal to the lung in the costophrenic recess. A hemothorax may have a simple anechoic appearance, but may also contain heterogeneous echoes from clotted blood or portion of lacerated lung tissue.

  • The presence of pleural fluid will allow direct visualization of the lung and posterior structures, including the vertebral bodies of the thoracic spine often referred to as the “spine sign” (Fig. 24.25).

FIGURE 24.25

Hemothorax. Fluid (in this case blood) is identified as an anechoic “wedge” above the diaphragm with loss of the normal mirroring artifact of the diaphragm allowing visualization of the spine extending beyond the costophrenic angle, also known as the “spine sign.” (Illustration contributor: Robinson M. Ferre, MD; ultrasound contributor: Jeremy S. Boyd, MD.)

Suspected Pneumothorax

  • When using ultrasound to evaluate for a pneumothorax, the transducer is placed in the superior most portion of the chest wall in a supine patient to assess for normal apposition of the pleura. Unlike chest radiography, ultrasound must look for normal apposition of the visceral and parietal portions of the pleura in a stepwise fashion. Indeed, it is important to note that ultrasound can only assess for the presence or absence of a pneumothorax in the area of the lung where the transducer is currently imaging. Thus, when using ultrasound, we assume that there is no prior history of pleural scarring or pleural adhesions.

  • With the indicator directed toward the patient’s head, the transducer is placed just below the clavicle in the midclavicular line. To provide maximum sensitivity for the presence of a pneumothorax, the probe should be dragged caudal in the midclavicular line until the diaphragm is seen just below the costal margin (Fig. ...

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